In the field of materials science, it is important to understand the relationship between the microscopic properties of a material and its macroscopic behavior. In the presented work, the authors aimed to clear up the theoretical interlink between local adhesion capacity and macroscopic fracture energies by bridging different length scales, such as nano-, meso-, and macro-scale. To achieve this, the authors used crystal plasticity theory along with a cohesive modelling approach.
The study focused on the influence of different cohesive law parameters, such as cohesive strength and work of adhesion, on the macroscopic fracture energies of three different orientations of niobium/alumina bicrystal specimens.
The results showed that cohesive strength had a stronger effect on the macroscopic fracture energies as compared to work of adhesion. The relation between cohesive strength and fracture energy was found to be non-linear cubic, while the relation between work of adhesion and fracture energy was almost linear. It was also noted that the set of cohesive law parameters found for the niobium/alumina bicrystal specimens for the three different orientations was not unique and several combinations of cohesive law parameters could validate experimental results.
In the last part of the work, the authors derived a generalized correlation between the fracture energy, cohesive strength, work of adhesion, and yield stress. This correlation interlinked the local adhesion capacity, cohesive strength, yield stress, and macroscopic fracture energy for the niobium/alumina bicrystal specimens. This correlation can provide valuable information for experimentalists in designing better metal/ceramic interfaces.
In conclusion, the presented work highlights the importance of bridging different length scales in understanding the relationship between local adhesion capacity and macroscopic fracture energies. The results of this study can provide useful insights for further research in the field of materials science, specifically in the area of interface fracture analyses of bicrystal specimens.
 A. Siddiq, S. Schmauder, M. Ruehle, Niobium/alumina bicrystal interface fracture: A theoretical interlink between local adhesion capacity and macroscopic fracture energies, Engineering Fracture Mechanics, Volume 75, Issue 8, 2008, Pages 2320-2332.